factorize {QCA} | R Documentation |
This function finds all combinations of common factors in a Boolean expression written in SOP - Sum Of Products form.
factorize(input, snames = "", noflevels = NULL, pos = FALSE, use.tilde = FALSE, ...)
input |
A string containing the SOP expression, or an object of
class |
snames |
A string containing the sets' names, separated by commas. |
noflevels |
Numerical vector containing the number of levels for each set. |
pos |
Logical, if possible factorize using product(s) of sums. |
use.tilde |
Logical, use a tilde to negate the sets. |
... |
Other arguments (mainly for backwards compatibility). |
Factorization is a process of finding common factors in a Boolean expression, written in a SOP - sum of products (or DNF - disjunctive normal form). Whenever possible, the factorization can also be performed in a POS - product of sums form.
Conjunctions should preferably be indicated with a star *
sign, but this is not
necessary when conditions have single letters or when the expression is expressed in
multi-value notation.
The argument snames
is only needed when conjunctions are not indicated by
any sign, and the set names have more than one letter each (see function
translate()
for more details).
The number of levels in noflevels
is needed only when negating multivalue
conditions, and it should complement the snames
argument.
If input
is an object of class "qca"
(the result of the
minimize()
function), a factorization is performed
for each of the minimized solutions.
The argument use.tilde
is automatically activated if the input contains
a tilde to negate conditions.
A list with two components:
initial | The input expression. |
factored | All possible factorizations of the input expression. |
Adrian Dusa
Ragin, C.C. (1987) The Comparative Method. Moving beyond qualitative and quantitative strategies, Berkeley: University of California Press
# typical example with redundant conditions factorize("AbcD + AbCd + AbCD + ABCd") # results presented in alphabetical order factorize("one*TWO*four + one*THREE + THREE*four") # to preserve a certain order of the set names factorize("one*TWO*four + one*THREE + THREE*four", snames = "ONE, TWO, THREE, FOUR") factorize("~ONE*TWO*~FOUR + ~ONE*THREE + THREE*~FOUR", snames = "ONE, TWO, THREE, FOUR") # using pos - products of sums factorize("ac + aD + bc + bD", pos = TRUE) # using an object of class "qca" produced with minimize() data(CVF) pCVF <- minimize(CVF, outcome = "PROTEST", incl.cut = 0.8, include = "?", use.letters = TRUE) factorize(pCVF) # using an object of class "deMorgan" produced with negate() factorize(negate(pCVF))